Vehicles today may have different driving modes with different levels of activated arrangements and systems for relieving a vehicle operator from some or all operations he/she otherwise would have had to perform in order to drive the vehicle along a route.
A driving mode in which the vehicle operator himself/herself drives the vehicle along a route or road is referred to as a manual driving mode. In the manual driving mode the vehicle operator provides e.g. steering-, accelerating- and braking input to the vehicle.
Many vehicles provide some semi-autonomous functionality. For example, vehicles equipped with automatic or adaptive cruise control can control the host vehicle to keep a distance to a preceding vehicle such that e.g. rear-end collisions are avoided or mitigated. A lane keeping aid in a vehicle may control a lateral position of the host vehicle such that the vehicle follows a road lane, alternatively the aid can warn the operator when a road lane is crossed. When such system or systems are activated, a vehicle operator is relieved from the some tasks but has to continuously stay alert and be ready to manually interact and take over if necessary. Such a driving mode is referred to as a semi-autonomously driving mode.
Some vehicles today are capable of driving autonomously, i.e. without steering- accelerating- or braking input from a vehicle operator. Sensors of the autonomous vehicle continuously monitor the vehicle surrounding. The sensors can detect e.g. road lanes, surrounding traffic and various obstacles on- or in the vicinity of the road. The sensors may detect distance and direction to other vehicles, pedestrians, bicycles etc. Different kinds of sensors may be used, such as cameras, radar and/or lidar. Autonomous vehicles can also comprise communication equipment, such that road and/or traffic information may be sent to the vehicle. A drive arrangement of the vehicle can then control drive functions, such as steering, accelerating, braking etc. as a function of the information received from the sensors and information sent to the vehicle. Hereby the vehicle can drive autonomously along at least some road sections within a road network. A driving mode in which the vehicle is driving autonomously is referred to as an autonomous driving mode.
Autonomous drive functions may facilitate for a vehicle operator, since he/she may focus on secondary tasks instead of driving when autonomous driving is enabled. However, due to limitations of host vehicle functions or due to preferences from the vehicle operator, he/she may select to drive manually instead of using the autonomous drive mode.
Some requirements should be met before transitions between the different driving modes should be possible to initiate. For example, autonomous driving may be enabled only when the sensors provide the drive arrangement with sufficient information on the host vehicle surrounding. During a transition from an autonomous driving mode to a manual or semi-autonomous driving mode some other requirements may have to be met. It is desirable that it is clear to the vehicle operator when transitions are made, such that he/she knows which driving mode is being utilized at a certain moment. It is also desirable that transitions between the different driving modes are made in a smooth and secure manner. Thus, improvements related to transitions between different driving modes are desirable.